1. Field of Invention
The present invention relates generally to systems, methods, and software products for delivering content in client-server networks, and more particularly, to systems, methods, and software products that optimize the delivery of such content in response to optimization criteria.
2. Background of the Invention
The Internet generally, and the World Wide Web specifically, provide a client-server model of content delivery, in which content stored on a server at a web site is delivered over a communications channel to a client device. Conventionally, the content as structured by the author is delivered by the server to all requesting clients in the same form. That is, the server does not change the structure of the content to accommodate the performance characteristics of the communication channel to a particular client, or the performance characteristics of the client itself. At best, the client re-formats the received content based on its own capabilities (e.g. a text only browser will filter out images, but still must receive the images, thereby consuming bandwidth).
This delivery model is not satisfactory when there are many different types of clients, with varying performance capabilities and varying communication channels. For example, today a web site may be accessed by many different types of clients, from conventional full size computers with large screen displays (e.g. 13″ to 17″) and full color capabilities (16 M colors) to small handheld computers with small screens (e.g. 4″ to 6″) and limited color capabilities (256 colors), to cellular telephones with very small screens (1″–2″) and virtually no color capabilities (2–8 colors monochrome). A web page with many images that is designed to be viewed on a full size, full color monitor will not appear at all properly on a cellular telephone display with only monochrome output. Moreover, the cellular telephone has a much lower bandwidth capability than a standard desktop computer, and thus would require significantly more time (and hence more cost and delay) in loading such a web page.
Typically, in order to accommodate these varying capabilities, a server must maintain many different web sites or web pages, each designed to be served to a particular class of client. But this approach is very labor intensive, particularly for sites that must be updated frequently, since the many different sizes and content selections for a given page must be kept in synchrony to all have the same current content. Further, display capabilities are only one characteristic that affects client performance. Different client devices may operate with different bandwidth capabilities, having different processor and memory capacities, or even have different pricing schemes associated with retrieval of content. When considering the possible combinations of factors that affect client performance, such as bandwidth and display capabilities (to name just two), the number of different possible web sites that need to be maintained quickly becomes unmanageable.
An alternative solution to maintaining multiple web sites is to design web sites that are acceptable to only the lowest performance devices that are going to access the site. But this approach yields simple sites that do not fully allow higher performance devices to take advantage of their performance features.
Accordingly, it is desirable to provide a system, method, and software product that can optimize delivery of content to client devices in response to optimization criteria. In particular, it is desirable to provide a web server that can efficiently deliver content to client devices having varying bandwidth, display, and other performance characteristics.